No need to call rb_define_class/module_under_id

Classes/modules defined in a namespace are defined under ::Object
as usual (as without namespaces), and it'll be set into the const_tbl
of ::Object.
In namespaces, namespace objects' const_tbl is equal to the one of ::Object.
So constants of ::Object are just equal to constants of the namespace.

That means, top level classes/modules in a namespace can be referred
as namespace::KlassName without calling rb_define_class_under_id().

Author: tagomoris

class.c

@@ -1605,13 +1605,8 @@ VALUE
 rb_define_class(const char *name, VALUE super)
 {
     VALUE klass;
-    ID id;
-    const rb_namespace_t *ns = rb_current_namespace();
+    ID id = rb_intern(name);
 
-    id = rb_intern(name);
-    if (NAMESPACE_OPTIONAL_P(ns)) {
-        return rb_define_class_id_under(ns->ns_object, id, super);
-    }
     if (rb_const_defined(rb_cObject, id)) {
         klass = rb_const_get(rb_cObject, id);
         if (!RB_TYPE_P(klass, T_CLASS)) {
@@ -1723,13 +1718,8 @@ VALUE
 rb_define_module(const char *name)
 {
     VALUE module;
-    ID id;
-    const rb_namespace_t *ns = rb_current_namespace();
+    ID id = rb_intern(name);
 
-    id = rb_intern(name);
-    if (NAMESPACE_OPTIONAL_P(ns)) {
-        return rb_define_module_id_under(ns->ns_object, id);
-    }
     if (rb_const_defined(rb_cObject, id)) {
         module = rb_const_get(rb_cObject, id);
         if (!RB_TYPE_P(module, T_MODULE)) {

test/ruby/test_namespace.rb

@@ -715,6 +715,7 @@ def self.ns6_proc = ->(){ Namespace.current }
         def self.yield_block = yield
         def self.call_block(&b) = b.call
       end
+      FOO_NAME = Foo.name
       NS9 = Foo.new.ns4
       EOC
       ns.eval(code)
@@ -731,6 +732,9 @@ def self.call_block(&b) = b.call
       assert_equal outer, ns::Foo.yield_block{ Namespace.current } # method yields
       assert_equal outer, ns::Foo.call_block{ Namespace.current }  # method calls a block
       assert_equal ns, ns::NS9 # on TOP frame, referring a class in the current
+
+      assert_equal "Foo", ns::FOO_NAME
+      assert_equal "Foo", ns::Foo.name
     end;
   end